This invention relates to automatic air-conditioning apparatus, and more particularly to an automatic air-conditioning apparatus in which a microcomputer is used to control the internal temperature of the compartment of an automotive vehicle.
A conventional automatic air-conditioning apparatus for an automotive vehicle includes a blower motor for selectively drawing in internal air of the vehicle compartment or external air, an evaporator for removing moisture from the intake air and a hot-water heater for heating the dehumidified air. Various air distributing doors such as an air intake door, an air mixing door, a vent door, a bypass door and a floor door are suitably actuated to carry out desired conditioning of air thereby supplying conditioned air into the compartment of the vehicle. These doors are individually actuated by associated actuators controlled by a negative pressure or vacuum. These actuators are connected to a vacuum tank through a vacuum supply piping system and a vacuum selector. The control system of the conventional automatic air-conditioning apparatus includes a temperature controller controlling the internal temperature of the vehicle compartment in response to output signals from a compartment air temperature sensor, an external air temperature sensor, a temperature setting unit, a temperature-control feedback potentiometer and a mode selector selecting the system operation mode. The temperature controller controls a power servo for controlling the opening of the air mixing door, and it also controls the vacuum selector through the power servo. The vacuum selector selects the actuators to be driven, and the associated doors are actuated to control the internal temperature of the vehicle compartment.
However, the prior art automatic air-conditioning apparatus having such a construction has required a plurality of vacuum supply pipes resulting in a complex system construction due to the fact that all the doors are controlled by the vacuum supplied from the vacuum tank. Further, a temperature monitor for displaying a selected temperature setting has not been provided although a unit for setting the inernal temperature of the vehicle compartment (the internal air temperature) has been provided. The prior art automatic air-conditioning apparatus has not been capable of directly showing the actual temperature of internal air although an approximate value of such a temperature can be predicted, since a temperature monitor for displaying the internal temperature of the vehicle compartment is not provided. The prior art automatic air-conditioning apparatus has therefore been defective in that inconveniences are encountered and a considerable length of time is required until the internal temperature of the vehicle compartment is adjusted to a comfortable level when the number of occupants changes or the condition of radiation of daylight changes.